The problem I see with the above design is with the almost perpetual side thrust loading of the piston against the cylinder bore. Piston big-end and main bearing lubrication could also be a problem due to the one-sided motion (do a force analysis on a polar graph!) and the huge added inertial forces of all the additional masses moving all over the place.

This design is somewhat similar to a VCR concept by FEV (my former employer) where an eccentric takes the place if the crankshaft in the above animation to effect the adjustability for compression ratio. However, the crankshaft remains in the same location directly under the cylinder bore centerline (and can also be offset) to further minimize side thrust loading and the resultant bore distortion and uneven piston/cylinder wear.

Piston big-end and main bearing lubrication could also be a problem due to the one-sided motion (do a force analysis on a polar graph!) and the huge added inertial forces of all the additional masses moving all over the place.

Thanks for professional question.Its is no maximum excellent proposition. Its only "natural interesting detail ", for possible various design.But by the way ,additional masses not very big problem , because valve crankshaft are going twice slowly, and forces are four little.One CH physicist elegant describes this advantages: intake / inertia is better for valve piston than main piston Another "natural interesting detail " are crankshaft less design, right now see in other place.At 1925 Polish designer Tadeusz Tanski describe six cylinder some one :

Well, I don't see emissions being much of a problem with Feliks' engine- there is a number of valve types for 2T engines that could be perfect for the job (planar valves, reed valves, &c). Actually, I have fiddled with the idea of VVT for 2T valves, but after making a design, dropped it since 2T engines were forced almost into extinction...

Stian- I think the engine You presented doesn't neccessarily need a blower, a numer of 2T engines uses crankcase for that (downward movement of the piston forces the air from crankcase into the cylinder). BTW, I think Andrew was asking You how to change intake timing, and the answer is in my above post- put a planar valve on a crankshaft and rotating it one way or another...

Although I wouldn't use a belt to drive an opposing crank/piston setup as in your original proposed valving scheme, but for normal camshaft/poppet valve valvetrains it's an elegantly simple design to achieve VVT that I know works because I've seen the effects of a stretching timing belt on injection pump timing in my TDI engine as the eccentric tensioner, which works on a somewhat similar principle as above, takes up the slack.

Originally posted by AndrewD Control and adjustability would be hard, which is one bonus to the new hydraulic vane and screw type phasers.

Control and adjustability are amazingly easy; it's just some simple geometry and a linear actuator, which can be electric, hydraulic, pneumatic, whatever. The thing to consider is belt- or chain stretch as those parts wear, or the wearing of the polymer chain guides as those will effect the timing.

Stian- I think the engine You presented doesn't neccessarily need a blower, a numer of 2T engines uses crankcase for that (downward movement of the piston forces the air from crankcase into the cylinder). BTW, I think Andrew was asking You how to change intake timing, and the answer is in my above post- put a planar valve on a crankshaft and rotating it one way or another...

Yes you could use the crankcase, but then you get new problems with multi cylinder set up's and you would not get as good lubrication as you could with aspiration and crank separeated.

Also you would nead oil to mix in air to lubricate bearings and sutch making more carbons in the exhaust.

With eliminating crancase from the aspiration system you can inject the lubrication oil trough holes in the cylinder waal instead reducing the amount off oil neaded to keep a load bearing oil film on the cylinder waal.

Been there, done that, in about 1980 - Porche subsequently thought to Patent something similar some 10 years later.

My original drawings, done in RoboSolid, were published in a short lived Auto Technology magazine. It took me about 5 minutes to think of the idea - I thought that it was so simple, someone must have already done it, so I never applied for a Patent! In my design for Twin Cams there was a left to right slider which varied the phase of both cams in relation to the crankshaft, and a third roller between the cams which could, in conjunction with the lateral control, phase the camshafts in relation to each other and the crankshaft at the same time. I belive that I have the drawings on a 5.25" floppy, but I'm not sure I have a programme that can read them anymore - the magazine is, I think, somewhere in the loft under nearly 20 years of dust!

I also did two further designs using a) a differential, and b) epicyclic gears.

The differential system works like this:

Assume an old fashioned back axle, lock the propshaft and turn the RH wheel, the LH rotates in the opposite direction at the same speed as the RH wheel, right? If you lock the RH wheel and rotate the propshaft one revolution, the LH wheel rotates about 1/4 of a turn (Assuming a 4:1 Diff ratio), agreed? If you rotate the RH wheel so that the LH wheel is turning, then rotate the propshaft 1/4, turn the LH wheel will still be rotating at the same speed as the RH wheel, but 90 degrees out of phase. Now imagine that the RH wheel is the Timing Gear driven by the crankshaft, and the LH wheel is the camshaft, and that your Pinion Gear is servo controlled, and Bob's your Uncle.

The Epicyclic system is very similar, the Sun Gear is on the Camshaft, the Planetary gears are driven from the Crankshaft, and the phasing is servo controlled via the Ring Gear.

The latter two systems are so much simpler than the oil pressure driven Alfa Romeo system, using a helical plunger, that originally caused me to consider methods, that I again assumed that they had already been thought of - I could have been rich; rich I tell you: rich beyond the dreams of avarice - or ripped off by the big boys.........

Yes I know that the crank pulley should be 1/2 the size!!!! It was a quick sketch......

Quick and right: lower crank-valve , and upper two work normal cylinders. Take power and cloth on valve-crankshaft.!!! For me once of designs piston valve.Advantages- two little RPM and two more torque on take power

Originally posted by jo-briggs
[B]A sketch of my variable timing with a cam belt or chain.

If I understand your illustration correctly, the top vertically moving idler affects the phasing timing between the two camshafts, while the two horizontal idlers adjust the total timing advance and retard of both cams simultaneously.

The problem with your apparent independently moving idlers is that as they move relative to each other, the belt tension changes!! With Feliks' scheme, where the device moves with only one degree of freedom symmetrically on both sides, the belt path length remains constant, and therefore so does belt tension.

Also remember that belts and chains require a certain minimum "wrap-around" or engagement angle around a pulley, usually more than 180 degrees depending on the transmitted torque and a number of other factors. That's why idlers are strategically placed where they are.

Originally posted by TDIMeister Also remember that belts and chains require a certain minimum "wrap-around" or engagement angle around a pulley, usually more than 180 degrees depending on the transmitted torque and a number of other factors. That's why idlers are strategically placed where they are.

(Currently working at Gates...)

I very much doubt that most belt driven TwinCams have "Over 180 degrees" wrap round, in fact I've never seen pictures of any with a 180 deg wrap round. Some crankshaft pulleys approach that, but casm pullys can be about 100/110 Deg.

I very much doubt that most belt driven TwinCams have "Over 180 degrees" wrap round, in fact I've never seen pictures of any with a 180 deg wrap round. Some crankshaft pulleys approach that, but casm pullys can be about 100/110 Deg.

I was mistaken about the figure of 180 degrees for belt wraparound. Sorry -- I don't work in the belts department but am in the same office with colleagues who design them as well as tensioner systems for OEMs. You pick some things up from osmosis just from being in the vicinity.

My point was, exact numbers notwithstanding, that a certain minimum wraparound was necessary, and having any such scheme as a moving idler to effect variable timing as you suggested results in a change in the wraparound angle, and perhaps more importantly, in actual belt tension. These are not unaddressable issues but should nonetheless be considered, and I don't know if this was in fact thought about, so I just wanted to bring it to light.

The problem I see with the above design is with the almost perpetual side thrust loading of the piston against the cylinder bore. Piston big-end and main bearing lubrication could also be a problem due to the one-sided motion (do a force analysis on a polar graph!) and the huge added inertial forces of all the additional masses moving all over the place.

This design is somewhat similar to a VCR concept by FEV (my former employer) where an eccentric takes the place if the crankshaft in the above animation to effect the adjustability for compression ratio. However, the crankshaft remains in the same location directly under the cylinder bore centerline (and can also be offset) to further minimize side thrust loading and the resultant bore distortion and uneven piston/cylinder wear.

One big advantage have “piston Pivot”. Pistons not have force: Nm !!! This reaction is only in bearing piston !!

Another, piston no need lubrication , lubrication only need “Rings” (sliding seals) Next my modification: sliding seals put no in piston. This seals put in cylinder !! Advantages: cylinder are LIFETIME , ma-by building only aluminum cast . Because on cylinder no sliding piston and seals, made aluminum, excellent conduct heat !! But piston must make steel cast. (Or steel surface) Then piston and seals only need change at refit engine , without any mechanical engined. Theoretical, only need to change part to repair engine! In this version lubrications are need only seals, sure much little in conventional piston. Ma-by using conventional popped valve too.Are you like square pistons now ??

Important question: "cylinder" ,house of seals, and "piston" are very well cooling water.And temperature this elements are only few grad. more than temperature water. Maybe no Teflon, good material e.g .VITON® Regards Andrew

Originally posted by Feliks Important question: "cylinder" ,house of seals, and "piston" are very well cooling water.And temperature this elements are only few grad. more than temperature water. Maybe no Teflon, good material e.g .VITON® Regards Andrew

I like that first animation.
Just out of curisosity, how might you figure out what RPM it's going when it's fast.
I've always wanted to see what the inside of an actual engine looks like when it's running. Ages ago I saw some sort of video demonstration of a NASCAR (or similar) engine without the cylinder heads being turned at 3000rpm. The guy wrote his name with a pencil across the pistons.

A very good design for the reasons you point out but a few points id like to add-

If the partitions between chambers were attached to the engine block they would imho be strong, better cooled and less complicated around the centre pin assembly

Your going to have ubbbbbbbbber trouble getting even the best machinest to make up those curved edges to the exact sealing tolerances with massive friction once the engines warmed up. However an apex seal like the wankel engine uses ont he leading and trailing edge of each 'blade' facing opposite ways would do the job brilliantly i think.

Also you show the larger engines still running only one rod and imho thats going to put massivley un even stress on the front of the engine and i think at least one either end and maybe one in the middle on larger engines to reduce torque twist in the crank and crank sag would be much safer

Our new X4 2.4 litre engine is under 100kg in billet. The block is 160mm front to back. We have reached efficiency levels of the Toyota Prius engine per litre and will exceed this over the next month.

Too heavy?....BMWs 2.5 litre engine is 171kg....Our new 2.4 litre engine is 50% the total size and is currently 60% of the weight. We will soon lighten the engine down to 80-85kg making it half the weight.Latest news on our website www.revetec.com shows a CAD drawing of our latest engine.

The 'offset' look of the trilobes in some pics is because they are counter-rotating.

Am I right to interpret that data as telling us that the revetec delivers more peak power at full throttle, (presumably with lower fuel consumption as it is achieved with a smaller displacement and lower rpm peak) and it suggests that it is a more tractable engine at full throttle?

Sounds good but it's not everything, as you say (especially given the standard it's being compared to). Though from the look of the engine there shouldn't be a significant difference in volume/weight compared to a standard crankshaft engine. Cost, part-throttle efficiency and reliability remain to be seen then.

On the other hand (and this is the dreamer in me talking now) as the regenerative component of hybrid systems becomes more capable, the IC engine component can be downsized so that it is increasingly used at full or near-full throttle. Thus part-throttle efficiency may start to move down the list of priorities somewhat, which makes the comparison to the Prius engine a little more interesting. Not to suggest that there is anything wrong with the part-throttle performance of the engine, of course.

Big difference from a conventional rotary is that it does not drag the charge around, it would be more economical than the current rotary design since it would operate more like a four stroke. Just think how many valves can be added.

Originally posted by Powersteer Big difference from a conventional rotary is that it does not drag the charge around, it would be more economical than the current rotary design since it would operate more like a four stroke. Just think how many valves can be added.

The combustion chamber is still a pretty funny shape, and the face seals are going to be a bit awkward. But you do also get better control of the exhaust/intake. A Wankel necessarily opens its exhaust port before the end of the power stroke, which is less than ideal, although it compensates by leaving its intake port open the same length of time through the compression stroke. This engine could conceivably run on Atkinson/Miller cycle.